Rebecca,
The space is, unfortunately, not something we can fix right now. It's a problem with Facebook's widget where they add the space there 'in case' there are comments. There's been a bug report submitted to them to remove this area if there are no comments for the currently shown article. Additionally, we have plans to revise how comments are shown in an upcoming update (July timeframe), which should fix this issue. Unfortunately, until then, there aren't any easy fixes for the problem. Hopefully, Facebook will correct this soon.
As for putting it before the read more box, again, that's something we can't do easily. We use a plugin to insert the comment box, and the plugin group is called before the Read More is automatically inserted into the article by Joomla itself. It is, again, something we're looking on improving because it's been requested before. However, using Joomla's content plugin group makes it not-possible to do what you're looking for. With our upcoming updates to the commenting logic, this will be something we're hoping to add as well.
Finally, I'm not sure what you mean by the length of the comments box..? There is a setting to show how many comments it should show when automatically added, but there's not a way to individually set the length of the box per article. Hopefully, that's what you're looking for, but if not, just let us know!
Thanks,
Alex
Comments with inch space after article
